Features: Designed for acoustic guitar with 101-103mm sound hole diameter. as a guitar humidifier, simply moisten included sponge and install for reusable humidification. Working as a guitar dehumidifier, using included desiccant to absorb moisture around your guitar. Can also be as a normal sound hole cover to eliminate unwanted feedback. Soft rubber covers insert edge, no damage to your guitar. Specifications: Material: + Rubber Compatible Sound Hole Size: Dia 101-103mm Item Size: 11 * 1cm / 4.3 * 0.4oz Item Weight: 53g / 1.9oz Package Size: 14 * 12 * 3cm / 5.5 * 4.7 * 1.2in Package Weight: 102g / 3.6oz Note: This sound hole cover is not suitable for guitars whose fretboard has reached sound hole. guitar showed in picture is not included. Package List: 1 * Sound Hole Cover 1 * Sponge 1 * Bag of Desiccant Designed for acoustic guitar with 101-103mm sound hole diameter. Working as a guitar dehumidifier, using included desiccant to absorb moisture around your guitar. Used as a guitar humidifier, simply moisten included sponge and install for reusable humidification. Soft rubber covers insert edge, no damage to your guitar. Can also be used as a normal sound hole cover to eliminate unwanted feedback.